Bobbin housing for double stitch sewing machines



Sept. 18, 1962 H. ADAM 3,054,369

BOBBIN HOUSING FOR DOUBLE STITCH SEWING MACHINES Filed Aug. 1958 59.1 Tr'j L I l?! fi -LF' 47% gf -1 United States Patent 3,054,369 BOBBIN HOUSING FR DOUBLE STITCH SEWING MACImJES Hermann Adam, Bielefeld, Germany, assignor to Anker- Phoenix-Nahmaschiuen Aktiengesellschaft, Bielefeld, Germany Filed Aug. 6, 1958, Ser. No. 753,584 Claims priority, application Germany Aug. 8, 1957 2 Claims. (Cl. 112-231) Double stitch sewing machines having a freely rotating looper with bobbin housing support, of the type referred to as telescoping loopers, have the great advantage of being proof against blocking. In contrast to the so-called reciprocating grippers a thread which becomes wedged in the orbit of the looper can never bring the machine to a standstill. This advantage is obtained in that between the looper and the bobbin housing support there is suiiicient tolerance to permit the thread to slip through between the inner surface of the support and the back of the housing. However, this inestimable advantage of the telescoping looper is under some conditions accompanied by the shortcoming that the bobbin housing which is not guided may move back and forth between its path in the looper and its support and thus cause undesirable noise. Besides such uncontrolled movement of the bobbin housing may adversely affect the forming of stitches in that one or the other stitch is laterally displaced, thus departing from the straight line of the seam. The cause of this phenomenon is found in that during pulling of the thread while at the same time knotting the thread in the material, the bobbin housing is not pulled vertically upwardly, but rather tilts the housing and abuts against the inner surface of the mounting or support. These phenomena must be especially considered if the telescoping looper which rotates twice for each rotation of the arm shaft is to be adapted for high speed sewing conditions while at the same time obtaining the great advantage of safety against blocking in high speed sewing machines.

The solution of this problem was confronted with considerable diiculties, as extensive research and tests revealed that departures are necessary from the prior art structures particularly as to the position of the feeding of the thread out of the bobbin housing and the thread guiding from the bobbin housing to the stitch aperture in the stitch plate.

It is therefore an object of the invention to overcome in double stitch sewing machines having a twice rotating telescoping looper the aforementioned disadvantages, particularly the tilting of the bobbin housing.

In accordance with the invention the bobbin housing is constructed in such a manner that its center of gravity causes it to hang vertically downwardly with respect to the lower thread. For this purpose the thread exit aperture on the bobbin housing is located substantially in the vertical axis of the center of gravity. The nose having the thread aperture may in this connection be arranged ou the bobbin housing in such a manner that the bobbin housing is raised only vertically with respect to the needle aperture in the stitch plate of the sewing machine, i.e. the needle aperture of the stitch plate is disposed vertically above the thread aperture on the bobbin housing. It has been found that under these conditions the bobbin housing support can be mounted with a particularly great thread tolerance in a manner that without changing this adjustment, lit is possi-ble to utilize optionally very thin and very thick threads, for example, also woolen threads.

Bobbin housings provided with these features operate with considerably less noise, other conditions being the same, and they result at the same time in an even seam extending in a straight line, also in very rapidly running double stitch sewing machines.

Further objects and advantages of the invention .will become apparent from the following description of an embodiment illustrated in the accompanying drawings in which:

FIG. 1 is a side elevational view of the stitch forming portion of the sewing machine showing components cooperating with the subject of the invention in dot and dash lines,

FIG. 2 is a top view of the bobbin housing showing the guiding aperture for the thread extending inwardly toward the needle aperture,

FG. 3 is a side view of the bobbin housing in accordance with FIG. 2, and

FIG. 4 shows in dot and dash lines a side view of a bobbin housing provided with the conventional arrangement of the guiding aperture for the thread.

The drive for the looper 1 of the machine is derived from the main shaft, which is not shown, by way of the intermediate shaft 2. The intermediate shaft 2 is journalled in the base plate 3 and `supports at its forward end the worm gear 4 which engages the teeth of the cooperating gear 5, the axis of which is disposed at a angle with respect to the axis of the intermediate shaft. The gear 5 is secured upon the looper shaft 7 which is journalled in the bearing block 6 and carries at its projecting end the looper 1 which is driven at a 2 to 1 ratio. At the lower portion of the bearing block 6 the bobbin housing support 8 is securely mounted by means of a shoulder screw 9. The ring retaining member 11 is pivotally mounted for rocking movement in the direction of the looper by means of a piu 10 and supports the inner ring 12 as a counter support for the bobbin housing 13. The bobbin housing 13 having a thread feed slot 13a is provided with a projecting nose 14 presenting a thread guiding aperture 15 which is advantageously disposed in the proximity of the needle aperture 16 in the stitch plate 17, so that during sewing operations the lower thread 18 which hangs on the material being sewn and which moves horizontally on the stitch plate is pulled substantially vertically through the needle aperture 16 in a manner that the bobbin housing 13 is pulled upwardly without causing the bobbin housing 13 to tilt.

In accordance with the invention it is essential that for the operating condition of the sewing machine, particularly for the condition when the thread is being pulled, the center of the needle aperture 16 in the stitch plate 17, the center line of the thread guiding aperture 15 on the housing as well as the center of gravity of this housing are disposed in a substantially vertical plane in which also the thread 18 is disposed which is under tension. Thus, the bobbin housing 13, the end surfaces of which are disposed parallel to that plane, is actually suspended on the bottom thread 18 in a vertical position so that also the end surfaces of the housing are in vertical planes. A little gap is present between looper 1 and the proximate end surface of the housing 13 as well as also between the outer surface of the housing and the supporting ring 12, which gap is referred to as thread tolerance. By suspending the housing vertically the pull of the thread is effected only vertically and the housing is raised or lowered vertically over minute distances, so that tilting of the housing and friction between the surface of the looper 1 and the surface of the inner ring 12 such as the type of tilting which occurred in bobbin housing arrangements in accordance with FIG. 4 is avoided. It is known that such tilting and resulting friction, especially between ring 12 and the housing, is the cause of noises, so that in accordance with applicants construction substantially noiseless operation in that area is insured.

FIG. 4 of the drawing is intended to illustrate the difference between the subject of the invention and the conventional devices in accordance with the prior art. It is seen that heretofore the thread guiding aperture 15 was generally disposed along one side of an end surface of the bobbin housing and that, besides, no intentional efforts were made to eiect the pull of the thread from the bobbin housing toward the needle aperture in the stitch plate in a substantially vertical direction.

Having now described my invention with reference to the embodiment shown in the drawings, I do not wish to be limited thereto, but what I desire to protect by Letters Patent of the United States is Set forth in the appended claims.

I claim: Y 1. A bobbin housing and supporting means for a double rotation looper of double stitch sewing machines having a looper rotatably supported on a shaft, a stitch plate having a needle aperture, a bobbin housing received in said looper having an end surfaceV disposed substantially in a vertical plane, a bobbin supported in said housing, a retaining member having a ring for engagement with said bobbin housing and pivotally mounted below said bobbin housing, said bobbin housing having a thread feed slot and having a center of gravity disposed in a vertical plane extending parallel to said end surface, substantially perpendicularly with respect to said needle aperture and centrally of Vsaid slot, said bobbin housing having an inwardly and radially upwardly projectingnose portion having a thread guiding orifice disposed substantially vertically above the center of gravity of Said housing and having a center line disposed genin a vertical plane, a bobbin supported in said housing,

a retaining member having a ring for engagement with said bobbin housing and pivotally mounted below said lbobbin housing, said bobbin housing having a thread feed slot and having a center of gravity disposed in a vertical plane extendingparallel to said end surface, substantially perpendicularly with respect to said needle aperture and centrally of said slot, said bobbiu housing having an inwardly and radially upwardly Vprojecting nose portion having a thread guiding oriice disposed substantially vertically above the center of gravity of said housing and having a center line disposed generally ina vertical plane with the center line of said slot and with the center of said needle aperture, said nose portion extending rearwardly of said end surface of said bobbin housing and said orifice' extending substantially at right angles to a vertical plane through the axis of said housing proximate one end of said slot.

Flanagan May 8, 1906 Francis Oct. 2, 1917 

